1. Field of the Invention
The present invention relates to a high voltage transformer and microwave oven provided with the same, which allows an insulation distance between the output terminals of a secondary coil and a core to be extended, thereby improving an insulating effect.
2. Description of the Related Art
A high voltage transformer is a device that serves to boost an input voltage supplied from an external power supply to a high voltage and output the boosted voltage, and is generally used in electronic products, such as a microwave oven.
The high voltage transformer used in a microwave oven is manufactured by joining a laminated E core containing E iron cores, with a laminated I core containing I iron cores. Electrical parts, such as a primary coil, a secondary coil, pass cores and a heater coil, are disposed between the laminated E core and the laminated I core. The electrical parts are insulated by surrounding them with insulating papers such as NOMEX papers.
The high voltage transformer includes output terminals to output a boosted voltage. The output terminals are electrically connected to the secondary coil. The microwave oven, to which the high voltage transformer is applied, includes a high voltage circuit unit that applies a driving voltage to a magnetron. The output terminals of the high voltage transformer are electrically connected to the high voltage circuit unit such that the output terminals of the high voltage transformer serve as a connecter that supplies the boosted voltage to the high voltage circuit unit.
A conventional high voltage transformer is manufactured by assembling electrical parts, insulating the electrical parts, such as the primary and second coils, by surrounding them with insulating papers, and performing an infiltration process of soaking the assembled electrical parts in varnish liquid.
The output terminals of the high voltage transformer are mounted on a terminal support made of insulating papers because the terminals output a high voltage, and the output terminals are spaced apart from a grounded core by a certain distance.
In order to ensure a sufficient insulation performance, international standards organizations require that an insulation distance is extended between each of the output terminals of the high voltage transformer and the core. That is, the international standard organizations set a distance to be extended between each of the output terminals of the high voltage transformer and the core. To satisfy the requirement imposed by the international standards organizations, the thickness of the terminal support to fix the output terminals is allowed to be thick and, therefore, the output terminals are spaced apart from the core. However, if the terminal support formed by the insulating paper is excessively thick, it is difficult to fix the terminal support to the second coil and to fix the output terminals to the terminal support, so that assembly time is lengthened and the output terminals may be extended out of the high voltage transformer. Accordingly, the total size of the high voltage transformer is increased, so that the high voltage transformer occupies an excessive space in a microwave oven when the high voltage transformer is mounted in the microwave oven and, therefore, miniaturization of a product is hindered.